What is the most common organism responsible for paronychia?

Most Common Organism for Paronychia

Staphylococcus aureus is the most common organism responsible for acute paronychia, while Candida species (particularly C. albicans and C. parapsilosis) are the most common organisms in chronic paronychia. 1

Acute vs. Chronic Paronychia

Acute Paronychia

• Caused primarily by bacterial infections
• Most commonly Staphylococcus aureus 2, 1
• Often polymicrobial in nature, especially in children with oral habits
• Methicillin-resistant Staphylococcus aureus (MRSA) can be found in some cases 2
• Typically follows trauma or breach of the protective nail barrier

Chronic Paronychia

• Duration of at least six weeks 1
• Primary etiology is irritant dermatitis rather than infection
• Candida species are frequently involved as secondary colonizers
  • C. albicans and C. parapsilosis are most common 3
• Occurs more commonly in people with wet occupations 3
• More common in women than men 3
• Fingernails affected more often than toenails 3

Pathophysiology

• Acute paronychia develops when the seal between the nail fold and nail plate is disrupted, creating an entry portal for bacteria 4
• Chronic paronychia represents an irritant dermatitis to the breached nail barrier 1
• In chronic cases, the cuticle becomes detached from the nail plate, losing its water-tight properties 3
• Microorganisms (both yeasts and bacteria) enter the subcuticular space, causing further cuticular detachment 3
• Secondary bacterial or fungal superinfections are present in up to 25% of cases 3

Clinical Presentation

• Acute paronychia: Painful erythematous inflammation with swelling and tenderness of the lateral nail folds 3
• Chronic paronychia:
  • Swelling of the posterior nail fold
  • White, green, or black marks in the proximal and lateral portions of the nail
  • Nail becomes opaque with transverse or longitudinal furrowing or pitting 3
  • Nail becomes friable and may detach from its bed

Management Considerations

• For acute paronychia:

  • Warm soaks with or without Burow solution or 1% acetic acid
  • Drainage if abscess is present
  • Topical antibiotics with or without steroids 1
  • Oral antibiotics only if immunocompromised or severe infection

• For chronic paronychia:

  • Remove exposure to irritants
  • Topical steroids or calcineurin inhibitors
  • Antimicrobial treatment if secondary infection present 1
  • For Candida-associated chronic paronychia, topical antifungals may be beneficial 5

Important Caveats

• Bacterial cultures should be obtained if infection is suspected, particularly in cases not responding to initial therapy 3
• In children with oral habits (thumb sucking), mixed anaerobic and aerobic infections are more common 2
• Chronic paronychia unresponsive to standard treatment should be investigated for unusual causes, including malignancy 4
• Prevention is critical, especially in occupational cases, including avoiding repeated trauma, wearing gloves while cleaning, and proper nail care 3